The invention relates generally to electrical conductor assemblies for conveying electrical signals between rotatably connected first and second members. More particularly, the invention relates to a flat, spirally-wound, multi-conductor cable assembly for conducting electrical signals between the relatively stationary steering column and relatively rotatable steering wheel of a vehicle.
In a steering wheel system, the established way of conveying electrical switching signals from the revolving steering wheel to the stationary steering column has been through the use of slip ring and brush assemblies. Because steering wheels must rotate several full turns in each direction (e.g. five turns from lock to lock), individual solid conductor wires have not proven practical.
While the use of slip ring and brush technology is generally adequate for controlling the vehicle horn, this technology does not work well with multi-function steering wheel systems. In multi-function steering wheel systems a plurality of different functions are conveniently provided on the steering wheel, usually on a centrally-located keypad forming the hub of the steering wheel. Such a multi-function steering wheel may, for example, provide keypad control of vehicle functions and devices, including cruise control, horn, headlights, high beam/low beam, windshield washer and wiper, radio tuning and volume, and so forth. Slip ring and brush technology has not proven practical in the implementation of such multi-function steering wheels, in part due to space limitations preventing multiple slip rings and separate brush assemblies for each function and also due to conductivity problems with slip rings and brushes. In addition, slip rings and brushes produce audible noise, particularly when dirty, and are relatively expensive.
In response to the growing demand for multi-function steering wheels, the Sheller-Globe Corporation, Assignee of the present invention, has developed a multi-function steering wheel employing a radiant energy link between the rotatable steering wheel and stationary steering column, using optoelectronic devices. For a further understanding of this multi-function steering wheel technology, reference may be had to copending U.S. patent application Ser. No. 475,891, filed Mar. 16, 1983 entitled "Multifunction Steering Wheel"; and U.S. patent application Ser. No. 560,550, filed Dec. 12, 1983 entitled "Multifunction Steering Wheel". Both of said patent applications are assigned to the Assignee of the present invention.
To complement the above-described multi-function steering wheel technology, and to provide an economical and reliable alternative to the optoelectronic technology, the present invention provides a conductor assembly for conveying electrical signals between rotatably connected first and second members. The invention comprises a means for defining an enclosure carried on one of the first and second members, the enclosure defining an axis. The enclosure may be fashioned as two interfitting halves, one half coupled to the steering column and the other half coupled to the steering wheel. An elongated and flexible ribbon-like conductive cable is disposed within the enclosure and provides multiple conductive current conductive courses which are arranged substantially parallel to one another in a plane curving about the axis in spiral fashion. A first connector is electrically coupled to the conductive courses and is carried in fixed relationship to the steering column, while a second conductor is electrically coupled to the conductive courses and is carried in fixed relationship to the steering wheel. These electrical connectors are disposed at opposite ends of the ribbon-like cable and are carried upon the respective halves of the enclosure to retain the ribbon-like cable within the enclosure.
The ribbon-like cable is of a length permitting unrestrained rotation of the steering wheel from lock to lock. The cable length is such that rotation from lock to lock causes the cable to double back upon itself, whereby at one extreme end of rotation it is spirally clockwise wound and at the other extreme end of rotation it is spirally counter clockwise wound. The first and second connectors receive the ribbon-like cable in a slotted opening having flared and rounded edges to relieve strain and to prevent the cable from being kinked or sharply bent. The multiple conductive course are usable to convey control signals to individual vehicle devices and functions, wherein each conductive course is dedicated to the control of one such device or function. Alternatively, the conductive courses may convey multiplexed control signals, wherein one or more individual conductive courses control the operation of several devices or functions, each device or function responsive to its own unique encoded signal.
For a more complete understanding of the invention, its objects and advantages, reference may be had to the following specification and to the accompanying drawings.